1. Field of the Invention
The present invention relates to a construction machine such as a hydraulic excavator equipped with an operation pattern switching valve.
2. Description of the Related Art
There is known a hydraulic excavator equipped with an operation pattern switching valve for selecting a combination pattern of both operating valve and control valve from among plural such combination patterns in accordance with the desire of an operator.
The switching valve is installed under a floor near the operator's feet sitting on an operator's seat. An upper frame of an upper rotating body is composed of a base plate and a floor plate disposed spacedly over the base plate. A small aperture called an operation port is formed in the floor plate and an operating lever is operated through the small aperture. Therefore, it is necessary to install the operating lever in a state permitting easy operation thereof from the operation port.
On an upper surface of the switching valve a switching position is indicated using a cast letter or a sticker. For confirming that position it is desirable that as wide an area as possible on the upper surface side be easily visible from the operation port.
However, a large control valve unit is installed in a valve accommodating space and occupies most of the same, including a unit base, port and accessory pipes, so that the switching valve is compelled to be disposed behind the control valve unit and is installed at an inner position below a seat frame.
In this case, since the switching valve is installed perpendicularly to the base plate, its upper surface side also lies in the inner position.
On the other hand, since it is necessary to ensure a support portion for supporting a rear end portion of a floor mat laid over the floor plate, the operation port is formed in a position spaced a suitable distance forward from the seat frame.
As a result, since the whole of the switching valve is positioned fairly rearwards of the operation port, the operator is required to insert his or her hand backward through the operation port in a forcibly bowed state while looking at the inner side and is then required to operate an operating lever projecting slightly from the operation port. Thus, there has been the problem that not only it is very difficult to operate the operating lever, but also the indication of the switching position is difficult to see and it is difficult to check the position.
There also has been the problem that water sprinkled over the switching valve when washing the machine body is apt to stagnate on the upper surface of the switching valve, especially on a sealing member and a mounted portion thereof, and hence rusting is apt to occur.
The following measures are proposed against such problems.
(i) Disposing the switching valve just under the operation port (ahead of the present position) in a state in which a part of the valve overlaps the upper surface of the control valve unit.
(ii) Disposing the switching valve in a state in which its upper portion projects to the upper surface side of the floor plate, as disclosed in Japanese Patent Laid Open No. 2002-227249.
(iii) Installing the switching valve horizontally in the transverse direction at the present position and forming an operation port in a side face of the upper frame.
However, in the case of a small-sized hydraulic excavator whose height is limited, it is impossible to expand the valve accommodating space upward and hence the proposal (i) is unadoptable.
According to the proposal (ii), not only it is necessary to use an additional part for covering the projecting portion of the operating pattern switching valve, but also the projecting portion is an obstacle to washing the machine body. Further, the space near the operator's feet is reduced. Thus, the proposal (ii) is not advisable.
The proposal (iii) is not practical because not only it becomes difficult for the operator to perform operations but also it is necessary to provide a special lid for opening and closing the operation port.
Since an underfloor space is formed also on the right side between the upper frame base plate and the floor plate, the control valve unit or the switching valve can be displaced to the said right-hand underfloor space. Also in this case, however, the switching valve is still compelled to be installed in an inner position of the underfloor space. For example, this is because a swing cylinder for swinging a working attachment right and left is installed in front the switching valve. Thus, such displacement of the switching valve is not a solution to the foregoing problems.